Late cenozoic onset of the latitudinal diversity gradient of north American mammals

Jonathan D. Marcota, David L. Fox, Spencer R. Niebuhr

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35 Scopus citations


The decline of species richness from equator to pole, or latitudinal diversity gradient (LDG), is nearly universal among clades of living organisms, yet whether it was such a pervasive pattern in the geologic past remains uncertain. Here, we calculate the strength of the LDG for terrestrial mammals in North America over the past 65 My, using 27,903 fossil occurrences of Cenozoic terrestrial mammals from western North America downloaded from the Paleobiology Database. Accounting for temporal and spatial variation in sampling, the LDG was substantially weaker than it is today for most of the Cenozoic and the robust modern LDG of North American mammals evolved only over the last 4 My. The strength of the LDG correlates negatively with global temperature, suggesting a role of global climate patterns in the establishment and maintenance of the LDG for North American mammals.

Original languageEnglish (US)
Pages (from-to)7189-7194
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number26
StatePublished - Jun 28 2016

Bibliographical note

Funding Information:
Conversations with M. Kosnik, S. Lyons, S. Peters, and P. Wagner greatly improved the analytical design of this study. Portions of this work were supported by National Science Foundation Grant EAR 1252123 (to J.D.M.). This work is Paleobiology Database Publication 263.


  • Biogeography
  • Cenozoic
  • Climate
  • Latitudinal diversity gradient
  • Mammalia


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